1. Field of the Invention
The present invention relates to an FM transmitter which converts an audio stereo signal and the like to an FM signal, and transmits the FM signal.
2. Description of the Related Art
Conventionally, there is known an FM transmitter which is capable of converting an audio stereo signal to an FM signal and transmitting the FM signal, so as to enable an FM receiver arranged in the vicinity of the FM transmitter to output a sound (for example, Japanese Patent Laid-Open No. 2000-228635). In this FM transmitter, the oscillation frequency of a crystal oscillator is set to an integer multiple or an integer fraction of 7.6 MHz, and the oscillation signal of the oscillation frequency is frequency-divided to generate a signal of 38 kHz required for FM modulation processing and a reference frequency signal of 50 kHz required for a PLL circuit for outputting an FM broadcast wave. Such an arrangement, in which the oscillation signal of a single crystal oscillator is frequency-divided to generate two kinds of signals, makes it possible to simplify a constitution in comparison with a prior FM transmitter provided with two crystal oscillators.
However, in the above described FM transmitter, the oscillation frequency of the crystal oscillator is extremely limited because of the need to generate the signals of 38 kHz and 50 kHz by dividing the oscillation signal, which results in a problem that the degree of freedom in parts selection is low.